[Motor activity and heat loss in white mice in early ontogeny].

Studies have been made on motor activity, heat loss and body temperature in mice at the 5th, 7th, 9th and 11th days of postnatal life. Animals were exposed to temperatures of 30 and 36 degrees for 60-90 min. It was found that motor activity is higher in animals at earlier stages of postnatal development. Heat loss and body temperature do not depend on the level of motor activity. Motor activity is suggested to be a manifestation of behavioural thermoregulation in the newborn mice (which is essentially poikilothermic) rather than a significant source of additional heat production.